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Proving Triangles Congruent. F. B. A. C. E. D. The Idea of a Congruence. Two geometric figures with exactly the same size and shape. How much do you need to know. . . . . . about two triangles to prove that they are congruent?.
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Proving Triangles Congruent www.assignmentpoint.com
F B A C E D The Idea of a Congruence Two geometric figures with exactly the same size and shape. www.assignmentpoint.com
How much do you need to know. . . . . . about two triangles to prove that they are congruent? www.assignmentpoint.com
Corresponding Parts • AB DE • BC EF • AC DF • A D • B E • C F B A C E F D In Lesson 4.2, you learned that if all six pairs of corresponding parts (sides and angles) are congruent, then the triangles are congruent. ABC DEF www.assignmentpoint.com
SSS SAS ASA AAS Do you need all six ? NO ! www.assignmentpoint.com
Side-Side-Side (SSS) E B F A D C • AB DE • BC EF • AC DF ABC DEF www.assignmentpoint.com
Side-Angle-Side (SAS) B E F A C D • AB DE • A D • AC DF ABC DEF included angle www.assignmentpoint.com
Included Angle The angle between two sides H G I www.assignmentpoint.com
E Y S Included Angle Name the included angle: YE and ES ES and YS YS and YE E S Y www.assignmentpoint.com
Angle-Side-Angle (ASA) B E F A C D • A D • AB DE • B E ABC DEF included side www.assignmentpoint.com
Included Side The side between two angles GI GH HI www.assignmentpoint.com
E Y S Included Side Name the included angle: Y and E E and S S and Y YE ES SY www.assignmentpoint.com
Angle-Angle-Side (AAS) B E F A C D • A D • B E • BC EF ABC DEF Non-included side www.assignmentpoint.com
Warning: No SSA Postulate There is no such thing as an SSA postulate! E B F A C D NOT CONGRUENT www.assignmentpoint.com
Warning: No AAA Postulate There is no such thing as an AAA postulate! E B A C F D NOT CONGRUENT www.assignmentpoint.com
SSS correspondence • ASA correspondence • SAS correspondence • AAS correspondence • SSA correspondence • AAA correspondence The Congruence Postulates www.assignmentpoint.com
Name That Postulate (when possible) SAS ASA SSA SSS www.assignmentpoint.com
Name That Postulate (when possible) AAA ASA SSA SAS www.assignmentpoint.com
Name That Postulate (when possible) Vertical Angles Reflexive Property SAS SAS Reflexive Property Vertical Angles SSA SAS www.assignmentpoint.com
HW: Name That Postulate (when possible) www.assignmentpoint.com
HW: Name That Postulate (when possible) www.assignmentpoint.com
Let’s Practice ACFE Indicate the additional information needed to enable us to apply the specified congruence postulate. For ASA: B D For SAS: AF For AAS: www.assignmentpoint.com
HW Indicate the additional information needed to enable us to apply the specified congruence postulate. For ASA: For SAS: For AAS: www.assignmentpoint.com